Field of the Invention
The present invention relates to an engine system for a vehicle. More particularly, the present invention relates to an engine system for a vehicle that efficiently reduces a vibration of the engine generated due to an imbalance of rotational inertia during a valve idle in a diesel engine applied with a Cylinder Deactivation (CDA) function.
Description of Related Art
In general, internal combustion engines generate power by receiving and burning air and fuel in a combustion chamber.
That is, an intake valve is operated by a camshaft, and air is charged into the combustion chamber while an intake valve is open. An exhaust valve is also operated by a camshaft, and air is discharged from the combustion chamber while an exhaust valve is open.
The operation of the intake valve and the exhaust valve is changed depending on the rotation speed of the engine. That is, an appropriate lift or valve opening/closing time is changed depending on the rotation speed of the engine.
In order to implement appropriate valve operations according to rotation speeds of an engine, a variable valve lift (VVL) apparatus including a plurality of cams designed to have various shapes and driving a valve to be operated at different lifts according to RPM of an engine has been studied.
Also, a Cylinder Deactivation (CDA) apparatus selectively blocking combustion of some of the cylinders has been researched.
Here, the CDA apparatus deactivates some cylinders when the vehicle brakes or is driven with a constant speed, and during the operation of the CDA, the fuel supply to a deactivated cylinder to be a subject of the idle condition and the operation of intake/exhaust valves thereof are stopped.
In addition, due to regulations on carbon dioxide, vehicle makers are developing environmentally friendly diesel vehicles. The diesel engine has been known to have lower fuel consumption and better efficiency than the gasoline engine. In general, about a 40% better degree of efficiency occurs due to a high compression ratio of the diesel engine.
The diesel engine may also be applied with the CDA (Cylinder Deactivation) apparatus selectively blocking the combustion of some cylinders.
However, in the diesel engine applied with the CDA apparatus, if the function of the cylinder to be subjected to deactivation is stopped, a variation of rotational angular acceleration increases due to an imbalance of the rotational inertia between the cylinders, such that vibration of the engine is transmitted to the vehicle body such that the ride comfort is deteriorated.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.